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| Caucasopsiinae Chertoprud & Vinarski, in Chertoprud, Ekimova, Palatov, Grego, Mumladze et Vinarski, 2025 |
Highlights
• Hydrobiidae inhabit groundwaters on both south and north sides of the Great Caucasus.
• Caucasian hydrobiids are represented by three distinct phylogenetic lineages of subfamily taxonomical rank.
• A new subfamily of Hydrobiidae endemic to the Caucasus is described.
• A high morphological variability in the shell morphology within Caucasopsiinae subfam.nov. has been revealed.
• Female reproductive system morphology better supports high-level taxa phylogeny than other features.
Abstract
Hydrobiidae is the most diverse and species-rich freshwater gastropod family in the Palearctic. Their diversity in the Caucasus region remains largely unexplored and the phylogenetic relationships with European taxa have not been clarified yet. The primary objective of this study is to perform a molecular phylogenetic analysis of the stygobiotic Hydrobiidae of the Caucasus with an increased taxon sampling and incorporation of multiple molecular markers. We show that the Caucasian hydrobiids are represented by three distinct lineages of a subfamily rank: (1) Caucasopsiinae subfam. nov., comprises most of the stygobiotic hydrobiid genera endemic to Caucasus; (2) Belgrandiellinae includes a single stygobiotic genus Sitnikovia and a complex of crenobiotic genera; (3) Islamiinae is represented by a single monotypic genus. The Caucasian stygobiotic hydrobiids are represented by 13 genera, five of which were identified as new for science, and at least 37 species, including a significant number (20 species) of putative new taxa. Analysis of the soft-body anatomy revealed that the female reproductive system showed the best congruence with the phylogenetic relationships. Shell morphology showed high variability at both inter- and intrageneric level, questioning the generic assignment of species based on empty shells. The Caucasian stygobiotic Hydrobiidae show high endemism at all taxonomical levels from species to subfamilies, which probably reflects their long evolution in relative isolation from the hydrobiid clades inhabiting other regions.
Keywords: Groundwater ecosystems, Integrative taxonomy, Freshwater snails, Endemism, New Subfamily, Springsnails
Class Gastropoda Cuvier, 1795
Subclass Caenogastropoda Cox, 1960
Superfamily Truncatelloidea Gray, 1840
Family Hydrobiidae W. Stimpson, 1865
Subfamily Caucasopsiinae Chertoprud et Vinarski, n. Subf.
Type genus: Caucasopsis Grego et Mumladze, 2020
Type species: Caucasopsis letsurtsume Grego et Mumladze, 2020
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| Shells of Caucasian Hydrobiidae (SEM photographs): A – Caucasopsis sp. 3; B – Caucasopsis sp. 8; C – Caucasopsis letsurtsume, conic form; D – Caucasopsis letsurtsume, robust form; E – Pontohoratia birsteini; F – Caucasopsis vinarskii comb. nov.; G – Imeretiopsis gorgoleti; H – Schapsugia pulcherrima; I – Gen. 2; J – Gen. 1; K – Caucasogeyeria chrysomallos; L – Gen. 3; M – Sitnikovia megruli. |
Elizaveta Chertoprud, Irina Ekimova, Dmitry Palatov, Jozef Grego, Levan Mumladze and Maxim Vinarski. 2025. Little Treasures hidden in the Darkness: Diversity and Phylogeny of stygobiotic Hydrobiidae (Mollusca: Gastropoda) of the Caucasus. Molecular Phylogenetics and Evolution. 213, 108439. DOI: doi.org/10.1016/j.ympev.2025.108439
